Re: Dr Bussard's research

In article <uYGdnddofN4kGnjYnZ2dnUVZ_oSnnZ2d@xxxxxxx>,
"Paul F. Dietz" <dietz@xxxxxxx> wrote:

True. Can you give some examples, then?

LDX is my favorite (levitated dipole experiment at MIT).
Los Alamos works or has recently worked on on reversed field
configurations for magnetized target fusion. There's
current work on sperical tokamaks (NSTX) and compact
stellarators (NCSX), although one might not want to count
the former. And there's the entire inertial confinement
fusion effort.

Thanks, I'll have to look into these.

Did you actually watch the video? He wants to build an improved version
of his last subscale machine, incorporating the insights they gained
from those final experiments, and convene a review board to go over the
results and the theory to determine if it's worth pursuing further. He
doesn't strike me as somebody trying to cover up a failure.

You typically go to review *before* they give you money, Joe.
You're saying he doesn't need more grant money for his improved
machine?

No, engineering, fabrication, equipment, power, and personnel all cost
money. He needs about $2M to build that machine.

And he's working on a technical paper which will lay out all the physics
and math involved, as well as presenting experimental results in a more
rigorous form. That will be submitted to some standard physics journal,
I'm sure, and undergo the standard peer review.

So, a sensible funding schedule might wait to see this paper, gather
opinions on it from others in the field (taking into account possible
turf-protection that may influence some reviewers), and then assuming no
show-stoppers are uncovered, give him $2M and a year or so to build the
improved 0.1-scale machine and reproduce (and extend) those results.
Assuming those turn out as predicted, then go ahead and give him the
$150M to $200M to build the full breakeven-scale machine. He says there
is no new physics or engineering to be learned from building, say, a
half-scale machine, and I see no reason to doubt this.

So why the bitching about the tokamak mafia? They're
not as easy to fool as the Navy people he was getting his
money from?

Or, they're sucking billions of dollars into a project that is extremely
unlikely to work, diverting attention, money, and talent away from an
approach which is much more likely. I'd bitch about that too. It's not
politically savvy to do so, perhaps, but when you're nearly 80 years old
I think you feel a right to speak your mind.

Proton-boron fusion is extremely hard, and the confinement
necessary in a machine such as his is orders of magnitude beyond anything
he's achieved so far.

Yes, he admits that. He also says that energy output scales as the 7th
power of the machine size (and gain, i.e. output/input, scales as the
5th power of machine size).

Bzz. This is a seriously bad argument. You *don't* extend empirical
scaling laws through more than a limited range and expect them to hold.

So what? You're imagining that I'm making such an argument, and calling
it bad. But I didn't; I merely responded to your point, that he's got
many orders of magnitude to go, by pointing out that he readily admits
this and accounts for it in his calculations.

So now you will respond, so why does he think his 2-meter machine will
actually work? From what I gather, this is because the empirical
results obtained fit neatly with theory about what's going on. They can
explain all the losses, and have worked out an approach to minimizing
them which scales up.

There are good theoretical reasons why confinement in a tokamak is
significantly harder than confinement in a quasispherical potential
well. The difficulties of the former won't necessarily apply to the
latter.

The question here is can one reasonably expect this concept to lead
to a workable reactor, where confinement requirements are far more
strict than in his small reactors. It's often quite easy to make machines
with lousy confinement, even if there are fundamental physical effects
that will prevent any machines in the class from achieving good confinment.

I assume you meant "even if there are *no* fundamental physics effects
preventing good confinement." In other words, you're saying that the
engineering may be quite challenging even when the theory says it should
work.

Well, that may be; I haven't the expertise to judge. I suppose that,
based on an impartial review of the results from the improved 0.1-scale
machine, people may say that it's worth building a 0.5-scale machine
after all. If that costs significantly less than the full-scale
machine, and is likely to provide valuable insight, then it would be
worth doing. But if it's going to cost nearly as much as the full-scale
machine, and is unlikely to teach us anything we wouldn't learn from the
full attempt, then we should just go for it.

There is a significant cost to dilly-dallying; if going directly to full
scale will bring real power plants online 5 years sooner, then that's
almost certainly worth risking the extra up-front cost.

Best,
- Joe
.